Fuel oil composition



FUEL OIL COMPOSITION Paul Y. C. Gee, Woodbury, N. J., assignor to SoconyMobil Oil Company, Inc., a corporation of New York No Drawing.Application July 18, 1956 Serial No. 598,543

13 Claims. (Cl. 44-64) This invention has to do with improved fuel oilcompositions. More specifically it has to do with fuel oils which havebeen stabilized and which are particularly suitable for use asindustrial and domestic fuels.

Thefuel oils improved in accordance with this invention are hydrocarbonfractions having initial boiling points of at least 100 F. and end pointnot higher than about 750 F., and which boil substantially continuouslythroughout their distillation ranges. Such fuel oils are generally knownas distillate fuel oils. It is to be understood, however, that this termis not restricted to straightrun distillate fractions. Thus, as is wellknown to those skilled in the art, the distillate fuel oils can bestraightrun distillate fuel oil's, catalytically or thermally crackeddistillate fuel oils or mixtures of straight-run distillate naphthas andthe like, with cracked distillate stocks. Moreover, such fuel oils canbe treated in accordance with well known commercial methods, such as,acid 'or caustic treatment, solvent refining, clay treatment, etc.

The distillate fuel oils are characterized by their relatively lowviscosities, pour points and the like. The principal property whichcharacterizes the contemplated hydrocarbons fractions however, is thedistillation range. As mentioned hereinbefore, this range will liebetween about 100 F. and about 750 F. Obviously, the distillation rangeof each individual fuel oil will cover a narrower range falling,nevertheless, within the abovespecified limits. Likewise, each fuel oilwill boil substantially continuously throughout its distillation range.

The fuel oils particularly contemplated herein are Nos. 1, 2 and 3 fueloils used in domestic heating and as diesel fuel oils, particularlythose made up chiefly or en tirely of cracked distillate stocks. Thedomestic heating oils generally conform to the specification set forthin ASTM Specifications D39648T. The specifications for diesel fuels aredefined in ASTM Specifications D975- 4ST. Contemplated herein also arefuels for jet combustion engines. Typical jet fuels are defined inMilitary Specification MIL-F-5624B.

As is well known, fuel oils of the above-defined character have atendency to deteriorate in storage and to form colored bodies and sludgetherein. This deterioration of the oil is highly undesirable in that itcauses serious adverse efiects on the characteristics of the oil,particularly on the ignition and burning qualities thereof. It is also acontributory factor, along with the presence of other impurities in theoil, such as rust, dirt and moisture, in causing clogging of theequipment parts, such as screens, filters, nozzles, etc. as is explainedhereinbelow. An important economical factor is also involved in theproblem of oil deterioration in storage, viz., customer resistance.Thus, customers judge the quality of an oil by its color and theyoftentimes refuse to purchase highly colored oils.

Another and distinct problem that has plagued fuel oil manufacturers andusers is that referred to as screen clogging. This involves thedeposition of foreign subatent ce 2,849,301 Patented Aug. 26, 1958 wellas any sludge material formed by the deterioration said deposition offoreign substances.

of the oil, on the metallic surfaces of screens and filters of burnersand engines in which the oil is utilized. Additives have been developedto impart anti-clogging properties to fuel oils, functioning therein toinhibit the afore- The mechanism by which the clogging is preventedinvolves the adsorption of the anti-clogging agent or additive on themetal surfaces whereby the contacting of these surfaces by the foreignsubstances and/or preformed sludge is prevented.

In this way, deposition and build-up of these materials on the metalsurfaces is avoided. It will be appreciated, therefore, that the problemof preventing screen clogging by fuel oils is entirely different fromthat of preventing the formation of sediment and color therein as occursin the oil during prolonged periods of storage. Thus, it will beappreciated that any fuel distribution system will contain small amountsof foreign substances, such as condensed moisture and particles of rustand dirt, which become entrained in the oil, even though the oil has notbeen stored for any appreciable length of time. On the other hand, fueloils which have been in storage for substantial periods of time willalso contain another kind of sediment, or sludge, which is produced bythe gradual deterioration of the oil per se. This sediment, or sludge,is formed in the oil as the result of chemical phenomena. Thus, duringstorage, oxidation of the various c01n ponents of the oil, such aspyrrolic compounds; phenols and thiophenols present therein, takes placeforming quinoid molecules which condense with one another and/ or withother active hydrogen compounds also present in the oil to producehighly colored bodies of increasing molecular weight. When an oil hasbeen in storage for any substantial period of time these compoundsseparate out as insoluble sludge. Additives have also been developed toinhibit the formation of sediment or sludge inthe oil due to oxidativedeterioration of the oil in storage, as above described. Such additivesact by inhibiting the initial oxidation and the subsequent reactionswhich produce such sludge.

It is apparent, then, that the problem of preventing screen-clogging byfuel oils is entirely different from the problem of preventing theformation of sediment and color therein as occurs in the oil duringprolonged periods of storage. As evidence of the difference betweenthese problems, additives which prevent screen-clogging have generallylittle or no effectiveness in preventing the formation of sediment andcolor. Correspondingly, other additives which eifectively inhibitsediment and color formation generally have little or no anti-screenclogging properties.

This invention is primarily concerned with preventing or retardingscreen-clogging of fuel oils and the like, by

incorporating with said fuel oils a small amount of av novel additive.The invention is also concerned with overcoming the sediment and colorformation shortcomings of fuel oils, as well as-the screen-cloggingproblems, by incorporating with the fuel oils amounts of the noveladditive and other additives.

It is an object of this invention, therefore, to stabilize fuel oils.

It is a further object of this invention to provide a fuel oil free fromscreen-clogging tendencies.

Another object of the invention is to provide a fuel oil free fromscreen-clogging tendencies and stabilized against WhereinR is selectedfrom the group consisting of alkyl, alkenyl, alkynyl, cycloalkyl andaryl radicals, R is selected from the group consisting of hydrogen,alkyl, aryl and hetero radicals, and m and n are integers including andwhole numbers from 1 to 20 or more.

The esters described by the foregoing general formulae are prepared byreaction of one molar proportion of an aldehyde with one molarproportion of either an alkanol amine, a hydroxyalkyl polyalkyleneamineor a hydroxyalkyl hydrazine, to form a correspondingalkanolformaldimine; followed by reaction of one molar proportion of thelatter with one molar proportion of an organic monocarboxylic acid.These reactions are shown below in terms of the foregoing generalformulae:

Representative aldehydes suitable for use in preparing the desiredesters of this invention are: (1) aliphatic aldehydes such asformaldehyde, acetaldehyde, chloral, glyoxal, propionaldehyde,n-butyraldehyde, isobutyraldehyde, n-valeraldehyde, isovaleraldehyde,n-caproaldehyde, n-heptaldehyde, stearaldehyde, acrolein,crotonaldehyde, etc.; (2) aromatic aldehydes such as benzaldehyde,tolualdehydes, chlorobenzaldehydes, nitrobenzaldehydes,aminobenzaldehydes, salicylaldehyde, hydroxybenzaldehydes,methoxybenzaldehyde, anisealdehyde, p-dimethylamino-benzaldehyde, etc.;(3) heterocyclic aldehydes such as furfural, thiophene aldehyde, pyrrolealdehyde, etc. Preferred, herein, of such aldehydes is formaldehyde,which can be used in monomeric form or polymeric form such asparaformaldehyde.

Alkanol amines used in forming the esters are typified by:hydroxylamine, ethanolamine, propanolamine, butanolamine, etc. Preferredof such compounds is ethano1- amine.

Hydroxyalkyl polyalkyleneamines used herein are illustrated by:aminoethylethanolamine, aminopropylethanolamine,aininobutylethanolamine, aminoethylbutanoh amine, etc. Preferred of suchcompounds is aminoethylethanolamine.

Typical hydroxyalkyl hydrazines used in forming the desired esters are:hydroxyethylhydrazine, hydroxypropylhydrazine, hydroxybutylhydrazine,etc. Preferred of such compounds is hydroxyethylhydrazine.

Numerous types of organic acids can be used, and are so contemplated, informing the esters of this invention. These can be classified in thefollowing-manner:

.(l) Carboxylic acids of the aliphatic, aromatic-and .naphthenic types.

Typical aliphatic acids are formic, acetic, propionic, caprylic,decanoic, lauric, stearic, oleic, linoleic and abietic acids. Aromaticacids are illustrated by benzoic salicylic and phthalic acids, which mayor may not have aliphatic substituents such as diamyl benzoic acid,parafiin wax benzoic acid and the like. Of the carboxylic acids, thosehaving from about twelve to about eighteen carbon atoms per molecule arepreferred, and of these oleic acid is particularly preferred.

(2) Heterocycli-c acids such as thiophene carboxylic acid, furoic acids,pyrrole carboxylic acids and the like.

(3) Mixtures of such acids can also be used. For example, a mixture ofstearic and oleic acids is shown in one of the following illustrativeexamples. A commercial mixture is Indusoil which is a mixture of rosinacids and fatty acids. This has an acid number of 180l85; asaponification value of 181-186; and iodine number (Wijs) of 175-185. Itis comprised of 33-36% (weight) of rosin acids, 57-62% of fatty acidsand 5 7% of sterols. Another commercial mixture is Facoil CB which issimilar to Indusoil. It has an acid number of 166; a saponificationvalue of 174; and an iodine number of 143 (Wijs). It contains 45.4%(weight) of rosi acids, 47.8% of fatty acids and 6.6% of sterols.

It is to be understood that in order that an ester product havesatisfactory solubility in oil, proper combination of reactants must bemade. For example, when hydroxylamine is used as an alkanol amine, thealdehyde and/or acid with which it is associated should have. one ormore long chain aliphatic groups. In the same .connection, when an acidsuch as phthalic acid is used, an aldehyde and/or amine having one ormore aliphatic groups should be used. 1

The esters contemplated herein are used in fuel oils in concentrationsvarying between about 10 pounds per thousand barrels of oil, and about200 pounds per thousand barrels of oil. Preferably, the concentrationwill vary between about 25 and 100 pounds per thousand barrels. In termsof weight percent based upon the weight of the'fuel oil, theconcentrations vary preferably between about 0.01 percent and about 0.05percent.

As indicated above, the fuel oils of this invention can also contain, inaddition to the aforementioned esters, an addiitive serving as asedimentand color-forming inhibitor. Outstanding inhibitors whichcooperate with the esters are tertiary alkyl primary amines described inapplication Serial No. 299,249, filed July 16, 1952, now abandoned, andSerial No. 578,881, filed April 18, 1956. Briefly, such amines aretertiary alkyl, primary, monoamines having from about four to abouttwenty-four carbon atoms per molecule and having the primary aminonitrogen atom attached directly to a tertiary carbon atom. These aminesall contain the terminal unit:

Mixtures of the foregoing alkyl primary amines having from about 4 toabout 24 carbon atoms are also highly suitable for use in the invention.A typical mixture of amines, for example, is onecomprised of tertiaryalkyl primary amines of from about 12 to about 15 carbon atoms, saidmixture averaging about 12 carbon atoms per amine molecule. Thismixture, designated hereinafter as Mixture A, contains, by weight, aboutof tertiary dodecyl amine, about 10% tertiary pentadecyl amine andrelatively small amounts, i. e., less than about 5% of amines havingless than 12 or more than 15 carbon atoms.

Another mixture of tertiary alkyl primary amines which is highlysuitable for use in the inventon is composed of tertiary alkyl primaryamines of from about 18 to 24 carbon atoms and averaging about 20 carbonatoms per molecule.

This mixture designated herein as Mixture l3, contains the C -C tertiaryalkyl primary amines in about the following proportions:

The amount of tertiary alkyl, primary monoamine additives used, togetherwith the esters described above, can vary from about 25 to about 100pounds per thousand barrels of oil (i. e., about 0.01 percent to about0.05 percent by weight) depending upon the particular oil to bestabilized, and the conditions of storage.

Ifit is desired, the fuel oil compositions can contain other additivesfor the purpose of achieving other results. Thus, for example, there canbe present foam inhibitors, anti-rust agents, and ignition and burningquality improving agents. Examples of such additives are silicones,dinitropropane, amyl nitrate, metal sulfonates and the like.

The following specific examples are for the purpose of illustrating thefuel oil compositions of this invention and of exemplifying the specificnature thereof. It is to be understood, however, that this invention isnot to be limited by the particular additives and fuel oils, or to theoperations and manipulations described herein. Other esters of theabove-described character and fuel oils are utilizable, as those skilledin the art will readily appreciate.

EXAMPLE 1 A quantity (0.5 mol; 30.5 parts by weight) of ethanolamine wasadded gradually to a mixture of parts by weight (0.5 mol) ofparaformaldehyde and 87.8 parts by weight of benzene, as a diluent, at atemperature of about C. The mixture was stirred while the ethanolaminewas added, and stirring was continued throughout the preparation.Reaction between the amine and aldehyde was exothermic and thetemperature rose rapidly to 70 C. The resulting mixture was heated underbenzene reflux until the evolution of water of reaction ceased. Then,one hundred parts by weight (0.5 mol) of lauric acid were added. Themixture thus formed was heated gradually to 200 C. and was held at 200C. until water evolution ceased. The product, the lauric ester ofethanolformaldimine, was filtered through Hi-Flo Clay, a

1 diatomaceous earth. The product contains 4.7 percent of nitrogen, ascompared with a theoretical value of 5.5 percent.

EXAMPLE 2 Ethanolamine (2.25 mol; 137 parts by weight) was addedgradually to a mixture of paraformaldehyde (2.25 mol; 68 parts byweight) and 130 parts by weight of toluene, as a diluent, at 25 C.Again, stirring of the materials was maintained throughout thepreparation. The reaction was exothermic. The temperature rose rapidlyto 75 C. The resulting mixture was heated EXAMPLE 3 A quantity (0.5 mol;48 parts by weight) of furfural was added gradually to a mixture ofethanolamine (0.5 mol; 30.5 parts by weight) and toluene (100 parts by 6weight), at 25 C. Again, toluene was used as a diluent and stirring ofthe materials was continued during the preparation. Reaction wasexothermic. The temperature rose rapidly to C. After all of the furfuralhad been added, the resulting mixture was heated under toluene refluxuntil the evolution of water had ceased. Then, oleic acid 0.5 mol; 141parts by weight) was added to the above reaction mixture. The reactionmixture thus formed was heated gradually to 200 C. and was held at thelatter temperature until water and toluene were no longer evolved. Theproduct, the oleic ester of ethanolfurfuraldimine, contains 2.96 percentof nitrogen, in comparison with the theoretical value of 3.4 percent.

EXAMPLE 4 Fifty-five parts by weight of a 70 percent aqueous solution ofhydroxyethylhydrazine (0.5 mole; 38 parts by weight) were addedgradually to a mixture of paraformaldehyde (0.5 mol; 15 parts by weight)and toluene at about 25 C. Here, too, toluene was the diluent and thematerials used were stirred throughout the preparation. Reaction wasexothermic, with the temperature rising rapidly to 78 C. After thehydroxyethylhydrazine solution had been added, the resulting mixture washeated under toluene reflux until water was no longer evolved. Then,oleic acid (0.5 mol; 141 parts by weight) was added. The mixture soformed was heated gradually to 200 C. and was maintained at 200 C. untilthe evolution of water had ceased. The product, the oleic ester ofhydroxyethylhydrazoformaldimine, was filtered through Hi-Flo Clay. Thefilteredproduct has a nitrogen content of 5.26 percent, comparing withthe theoretical value of 7.9.

EXAMPLE 5 A quantity of 305 parts (0.5 mole) of ethanolamine was addedgradually at 25 C. to a mixture of 15 parts (0.5 mole) ofparaformaldehyde and cc. of benzene as a diluent with stirring. Thereaction was exothermic and the temperature rose rapidly to 70 C. Theresulting mixture was heated under benzene reflux until water stoppedcoming over. Then, 141 parts (0.5 mole) of oleic acid were added to thereaction mixture above. The mixture was gradually heated to 195 C. andwas held at 195 C. until water stopped coming over. The product, theoleic ester of ethanolformaldimine, was not filtered. Analysis: Nitrogenfound 4.69%; theory 5.5%.

EXAMPLE 6 A quantity of 75 parts (1.25 moles) of ethanolamine was addedgradually at 25 C. to a mixture of 37 parts (1.25 moles) ofparaformaldehyde and cc. of toluene as a diluent with stirring. Thereaction was exothermic and the temperature rose rapidly to 85 C., thendropped. The mixture was heated under toluene reflux until the evolutionof water ceased. Then 300 parts (approx. 1 mole) of Indusoil Tall oilwere added to the reaction mixture. The mixture was gradually heated to200 C. and was held at 200 C. until water and toluene stopped comingover. The product, a mixed ester of ethanolformaldimine, was filteredthrough Hi-Flo Clay. Analysis: Nitrogen found 3.72%; theory 3.9%.

EXAMPLE 7 A quantity of 61 parts (1 mole) of ethanolamine was graduallyadded at 25 C. to a mixture of 30 parts (1 mole) ofparaformaldehyde and150 cc. of toluene as a diluent with stirring. The reaction wasexothermic and the temperature rose rapidly to 85 C. then dropped. Themixture was heated under toluene reflux until the evolution of waterceased. Then, 280 parts (1 mole) of naphthenic acid were added to thereaction mixture. The mixture was gradually heated to 200 C. and washeld at 200 C. until water and toluene stopped coming over. The product,a naphthenic ester of formaldimine,

7 was filtered through Hi-Flo Clay. Analysis: Nitrogen found 3.56%;theory 4.1%.

EXAMPLE 8 Aquantity of 76 parts (1.25 moles) of ethanol-aminewas-gradually added at 25 C. to'amixture of 37.5 parts (1.25 moles) 'ofparaformaldehyde and 150 cc. of toluene as a diluent with stirring. Thereaction was exothermic and the temperature rose rapidly to 85 C., thendropped. The mixture was heated under toluene reflux until the evolutionof water ceased. Then, 340 parts (approx. l'mole) of Facoil 'CB wereadded to the reaction-mixture. The mixture was gradually heated to 200C. and was held at 200 C. until water and toluene stopped coming over.The product, a mixed ester of formaldimine, -was filtered through Hi-FloClay. Analysis: Nitrogen found 2.98%; theory 3.5%.

EXAMPLE 9 A quantity of 76 parts (1.25 moles) of ethanolamine wasgradually added at 25 C. to a mixture of 37.5 parts (1.25 moles) ofparaformaldehyde and 150 cc. of toluene as a diluent with stirring. Thereaction mixture was exothermic and the temperature rose rapidly to 80C., then dropped. The mixture was heated under toluene reflux until theevolution of water ceased. Then, 114 parts (0.4 mole) of stearic acidand 169 parts (0.6 mole) of oleyl acid were added to the reactionmixture. The mixture was gradually heated to 200 C. and was held at'200C. until water and toluene stopped coming over. The product, a mixtureof stearyl and oleyl esters of formaldimine, was filtered through Hi-FloClay. Analysis: Nitrogen found 3.7%; theory 4.1%.

EXAMPLE 10 A quantity of 25 parts (0.125 mole) ofamine Mixture A,described above, was gradually added at 25 C. to 25 parts (0.102 mole)of oleyl ester of ethanolformaldimine (Example 2, above), with stirring.No heat of reaction was observed. The mixture was stirred at 25 C. forthirty minutes.

EXAMPLE 11 'A quantity of 10 parts (0.05 mole) of amine Mixture A wasgradually added at 25 C. to 10 parts (0.04 mole) of lauryl ester ofethanolformaldimine (Example 1, above), with stirring. No'heat ofreaction was observed.

The mixture was stirred at 25 C. for thirty minutes.

EXAMPLE 12 8 EXAMPLE 13 :A quantity of 10 parts (0.05 mole) of amineMixture A was gradually addedat 25 C. to 10 parts (0.035 mole) ofstearic-oleyl ester of ethanolformaldimine (Example 9, above), withstirring. No-heat of reaction was observed. The mixture was stirredat25C."for thirty minutes.

EXAMPLE 14 A quantity of 10 parts (0.05 mole) of amine Mixture A wasgradually added at 25 C. to 10-parts (0.26 mole) of FacoilCB ester ofethanolformaldimine (Example 8, above), with stirring. No heat ofreaction was observed. The mixture was stirred at 25 C. for thirtyminutes.

The effectiveness of the additives of this invention in reducingscreen-clogging is shown by screen-clogging test data.

The amount of screen-clogging is determined witha Sunstrand V3 or S1home fuel oil burner pump having a self-contained mesh Monel metalscreen. About 0.05 percent, by weight, of a naturally-formed fuel oilsludge, composed of fuel oil, water, dirt, rust, and organic sediment,is added to ten liters of the fuel oil under test. This mixture iscirculated by the pump through the screen for six hours. Then the sludgedeposited on the screen is washed off with normal pentane, and filteredthrough a tarred asbestos (Gooch crucible) filter. After it is dried,the material on the filter is washed with .a 50-50 (volume)acetone-methanol mixture. The total amount of organic sediment isdetermined by evaporatingythe nepentane and the acetone-methanolfiltrates, and weighing the residue. The weight of material on thefilter is the amount of inorganic sediment deposited. The sum of theweights of the organic and the inorganic deposits, in milligrams, givesthe weight of .sludge deposited, which weight is compared with theWeight of sludge deposited from the uninhibited (blank) fuel oil todetermine the percent of screen-clogging. The uninhibited fuel oil,after six hours on test, eifects 100 percent screen-clogging. Thus, thecomparison percentagewise between the weight of sludge deposited by theuninhibited fuel oil and the inhibited fuel oil affords a measure of.the percent of screen-clogging. The fuel oil used in this test is ablend comprising sixty percent (by weight) of catalytically crackedcomponent .and forty percent -.of.straight run component, the blendhaving a boiling range from about 320 F., to about 640 F. The dataobtained from said tests are provided in Table I. Examples 1 through 9,inclusive, show fuei oils inhibited with the above-described esters.Examples 10 through 14, inclusive, show fuel oils inhibited with saidesters and amine mixtures.

Table I Example Product of- Screen clogging,

Aldehyde percent Hydroxyamme Furfural ParaformaldehydmHydroxyethylhydrazine... 25 Ethanolamlne 1 Amine used with ester.

Sedimentation tests were run on fuel oils and the same oils inhibitedwith the esters and amines described above in Examples 10 through 14. Inthe 110 F. storage test used, a 500-milliliter sample of the fuel oilunder test is placed in a convected oven maintained at 100 F., for aperiod of six weeks. Then, the sample is removed from the oven andcooked. The cooled sample is filtered through a tarred asbestos filter(Gooch crucible) to remove the insoluble matter. The weight of suchmatter, in milligrams, is reported as the amount of sediment. In thetest, a sample of the blank, uninhibited oil is run along with the fueloil blend under test. The effectiveness of fuel oil compositionscontaining the esters and amines of said Examples 10 through 14, isdetermined by comparing the test data therefor with the test data forthe unihibited, blank fuel oils. The results are given be low in TableII. The fuel oils used were of the same character as those describedabove in connection with Table I.

Table II Concn., Sedi- Inhibitor lb./1,000 ment,

bbls. rug/liter 158 +Example 100 18 0 111 +Example 11 100 19 0 122+Example 12 100 28 0 122 +Example 13 100 6 0 122 +Example 14- 100 20Although the present invention has been described in conjunction withpreferred embodiments, it is to be understood that modifications andvariations may be resorted to,'without departing from the spirit andscope of wherein R is a hydrocarbon radical, and n is an integer from 0to 20, and R is selected from the group consisting of hydrogen, alkyl,aryl, and hetero radicals,

R o o 0 0H, oHz)..NH(oH2 ,,.N=0-R' wherein R, R' and n are as describedin (a), and m is an integer from 0 to 20.

2. A distillate fuel oil containing a small amount,

. fromv about 0.01 to about 0.05 percent by weight of the fuel oil, afuel oil soluble ester of an organic acid and an alkanolformaldimine asdefined by claim 1.

3. A distillate fuel oil defined by claim 1 wherein thealkanolformaldimine is formed from an aldehyde and an alkanol amine.

4. A distillate fuel oil defined by claim 1 wherein thealkanolformaldimine is formed from an aldehyde and a hydroxyalkylhydrazine.

5. A distillate fuel oil defined by claim 1 wherein thealkanolformaldimine is formed from formaldehyde.

6. A distillate fuel oil defined by claim 1 wherein the organic acid isan aliphatic acid having from about twelve to about eighteen carbonatoms per molecule.

7. A distillate fuel oil containing a small amount, sufilcient to reducethe screen-clogging tendencies there-' of, of a fuel oil soluble esterof lauric acid and of an alkanolformaldimine formed from ethanolamineand formaldehyde.

8. A distillate fuel oil containing a small amount, sufficient to reducethe screen-clogging tendencies thereof, of a fuel oil soluble ester ofolcic acid and an alkanolformaldimine formed from ethanolamine andformaldehyde.

9. A distillate fuel oil containing a small amount, sufficient to reducethe screen-clogging tendencies thereof, of a fuel oil soluble ester ofoleic acid and an al kanolformaldimine formed from ethanolamine andfurfural.

10. A distillate fuel oil containing a small amount, sufficient toreduce the screen-clogging tendencies thereof, of a fuel oil solubleester of oleic acid and an alkanolformaldimine formed fromhydroxyethylhydrazine and formaldehyde.

11. A distillate fuel oil containing a small amount, suflicient toreduce the screen-clogging tendencies thereof, of a fuel oil solubleester of a naphthenic acid and an alkanolformaldimine formed fromformaldehyde and ethanolamine.

12. A distillate fuel oil containing a small amount, sufficient toimprove the screen clogging properties thereof, of a fuel oil solubleester of an organic acid and an alkanolformaldimine as defined by claim1, and a small amount, sufiicient to improve the resistance tosedimentation thereof, of a tertiary alkyl primary monoamine containingfrom four to about twenty-four carbon atoms per molecule andcharacterized by structural unit 13. A distillate fuel oil defined byclaim 12 wherein the monoamine is tertiary dodecyl amine.

References Cited in the file of this patent UNITED STATES PATENTS2,223,244 Bohm Nov. 26, 1940 2,346,663 Chenicek Apr. 18, 1944 2,361,339White et a1 Oct. 24, 1944 2,420,122 Chenicek May 6, 1947 2,564,106Gribbins et a1. Aug. 14, 1951 2,641,538 Thompson et al. June 9, 19532,641,539 Thompson et a1. June 9, 1953

1. A DISTILLATE FUEL OIL CONTAINING A SMALL AMOUNT, SUFFICIENT TO REDUCETHE SCREEN-CLOGGING TENDENCIES THEREOF, OF A FUEL OIL SOLUBLE ESTERSELECTED FROM THE GROUP CONSISTING OF: